Black spruce is monoecious. Female  flowers (ovulate strobili), produced in the upper meter of the crown, are  usually erect, cylindrical, and green or purplish. At the time of  fertilization, the female conelet is about 15 to 25 mm (0.6 to 1.0 in) in  length. The male flowers (staminate strobili), produced on the outer  branches of the crown below the zone of female flowers, are ovate, 12 to  20 mm (0.5 to 0.8 in) long and dark red to purplish during expansion. The  pollen sacs are yellow, and after pollen dispersal the staminate flowers  appear yellowish brown. A few cones may be produced after 10 years (2),  but the main cone-bearing age of black spruce is from 30 to 250, with  maximum production between 100 and 200 years (6).

    The flower buds formed by early August develop rapidly the following  spring. Female flowers are receptive and pollen is shed in late May or  early June in southern areas of the range and 1 to 2 weeks later in the  north. The female conelets then develop rapidly, and at maturity the cones  are 1 to 4 cm (0.4 to 1.6 in) long.